The vitamin D derivative represented by Formula (1):
(chemical name: [{(5Z,7E)-(1S,3R,20S)-1,3-dihydroxy-9,10-secopregna-5,7,10(19),16-tetraen-20-yl}oxy]-N-(2,2,3,3,3-pentafluoropropyl)acetamide, or [{1α,3β-dihydroxy-9,10-secopregna-5,7,10(19),16-tetraen-20(S)-yl}oxy]-N-(2,2,3,3,3-pentafluoropropyl)acetamide, or N-(2,2,3,3,3-pentafluoropropyl)-[{(1S,3R,5Z,7E,20S)-1,3-dihydroxy-9,10-secopregna-5,7,10(19),16-tetraen-20-yl}oxy]acetamide) exhibits useful human keratinocyte growth inhibition activity while its harmful calcium level-raising activity is lower than the conventional vitamin D derivatives, so that it is useful as a therapeutic agent for skin disorders such as psoriasis.
As a process for producing this compound, a process is known, in which [{1α,3β-bis(tert-butyldimethylsilyloxy)-9,10-secopregna-5,7,10(19),16-tetraen-20(S)-yl}oxy]acetic acid is reacted with 2,2,3,3,3-pentafluoropropylamine. See WO 2001/096293 (Patent Literature 1).    Patent Literature 1: WO 2001/096293